The present invention relates to data storage systems, and more particularly, this invention relates to a magnetic head and system implementing the same, where the head includes two offset transducer arrays oriented parallel to each other, longitudinally and opposingly offset from one another so that the two arrays do not overlap the same data tracks when reading and/or writing.
In magnetic storage systems, data is read from and written onto magnetic recording media utilizing magnetic transducers. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.
An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track and linear bit density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.
In a tape drive system, magnetic tape is moved over the surface of the tape head at high speed. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial so that the recording gaps of the transducers, which are the source of the magnetic recording flux, are in near contact with the tape to effect writing sharp transitions, and so that the read element is in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read element.
The quantity of data stored on a magnetic tape may be increased by increasing the number of data tracks across the tape. More tracks are made possible by reducing feature sizes of the readers and writers, such as by using thin-film fabrication techniques and MR sensors. However, for various reasons, the feature sizes of readers and writers cannot be arbitrarily reduced, and so factors such as lateral tape motion transients and tape lateral expansion and contraction (e.g., perpendicular to the intended direction of tape travel) must be balanced with reader/writer sizes that provide acceptable written tracks and readback signals. An issue limiting areal density is misregistration caused by tape lateral expansion and contraction. Tape dimensional instability (TDI) occurs when tape width varies by up to about 0.1% due to expansion and contraction caused by changes in humidity, tape tension, temperature, aging etc. Tilting, pivoting and/or rotating (used interchangeably herein as equivalent terms) of transducer arrays can compensate for misregistration due to TDI and keep the transducers aligned with tracks on the tape.
Inevitably, the desire to increase the rate at which data can be recorded to and read from a tape drive storage system to match the increasing processor rate of computers has led to increasing the number of readers and/or writers a single tape head module to up to, for example, 64 in a single array and all operating concurrently. However, a single array of 64 transducers in the same or smaller span than a previous array design limits the amount of adjustable space between channels in order to address TDI. Furthermore, the cables required per tape span for an array of 64 readers and/or writers may push the limits of flex circuit design and fabrication processing capabilities. Moreover, cables for servicing 64 readers and/or writers presents a significant problem in terms of congestion that may interfere with active track following, and may increase cross talk potential between the write channels or between write and read channels. As the tape capacity increases over generations, managing increasing numbers of reader and/or writer transducers and associated cabling requirements presents significant challenges and is a limiting factor for growing areal density.